Method for manufacturing semiconductor laser

Abstract

First, an active layer ( 3 ) of quantum well structure made of a semiconductor material is sandwiched by n-type and p-type clad layers ( 2, 4 ) made of a semiconductor material larger in band gap than the semiconductor of active layer, and a semiconductor laminate wafer ( 10 ) is formed so as to compose a laser resonator. The wafer is cleaved into bar form so as to expose end faces of the resonator. Further a thin film ( 11 ) containing a dopant is formed on at least one of the end faces of the resonator, and then end face coat films ( 12, 13 ) are formed. Thereafter it is heated to diffuse the dopant on the end face of the resonator. As a result, the band gap can be increased only on the resonator end face securely, and therefore this manufacturing method realizes a semiconductor laser having a window structure so as not to absorb light at the end face and capable of preventing deterioration of end face due to surface re-bonding.

What is claimed is:  
     
         1 . A method for manufacturing a semiconductor laser comprising the steps of: 
 forming a semiconductor laminate wafer to compose a laser resonator by sandwiching an active layer of quantum well structure made of a semiconductor material with n-type and p-type clad layers made of a semiconductor material of a larger band gap than said semiconductor material of active layer;    cleaving said wafer into bar form so as to expose end faces of said resonator;    forming a thin film containing a dopant on at least one of said end faces of said resonator;    forming end face coat films on said at least one of end faces; and    heating to diffuse said dopant into said at least one of end faces.    
     
     
         2 . The manufacturing method of  claim 1 , wherein said thin film containing the dopant is made of a material containing a metal which is more likely to oxidize than the material for composing said active layer and said clad layers.  
     
     
         3 . The manufacturing method of  claim 2 , wherein said thin film is formed by a metal layer of said metal.  
     
     
         4 . The manufacturing method of  claim 2 , wherein said thin film is composed of at least one of a metal-rich fluoride, a metal-rich nitride a metal-rich oxide and a metal-rich carbide which are excess in a metal content stoichiometrically.  
     
     
         5 . The manufacturing method of  claim 2 , wherein said metal is Mg.  
     
     
         6 . The manufacturing method of  claim 1 , wherein said thin film is formed in a thickness of several atomic layer or less.  
     
     
         7 . The manufacturing method of  claim 1 , wherein said heating is conducted by using a lamp to radiate only an end face part on which said thin film and said end face coat films are provided.  
     
     
         8 . The manufacturing method of  claim 7 , wherein said heating by said lamp is conducted by using a light at a wavelength having a band gap smaller than the band gap of said semiconductor substrate and said clad layers, and larger than the band gap of said active layer.  
     
     
         9 . The manufacturing method of  claim 8 , wherein said wavelength of the light is 0.8 to 1.1 μm.  
     
     
         10 . The manufacturing method of  claim 8 , wherein the light from said lamp is radiated by limiting to the light of said wavelength by using a wavelength filter.  
     
     
         11 . The manufacturing method of  claim 7 , wherein said heating by said lamp is conducted intermittently.